1. Field of the Invention
The present invention relates to an apparatus and method for compensating power of a power supply device in a vehicle using a high-capacitance capacitor.
2. Description of the Related Art
Although recent cars exhibit excellent performance, especially, near perfect combustion, due to development of various parts and Electronic Control Unit (ECU) software control technology, technical development is still needed to increase power transmission efficiency and to improve factors that affect the stability of ECU operation.
Future efforts should more focus on developing technical methods and mechanisms which can improve fuel efficiency (i.e., mileage) and performance of a vehicle by appropriately using engine force depending on travel situations when the vehicle travels.
For example, mileage is expected to be improved by 15% or more through eco-driving, i.e., by correcting inefficient drive behaviors such as sudden acceleration, sudden starts, sudden braking, and high-speed driving. However, such a mileage improvement method is not efficient since the effects of fuel economy-maximizing behaviors greatly vary among drivers and the effectiveness thereof is not always high.
That is, mileage improvement through change in driving behavior may not be effective since it is not practical to request such driving behaviors from drivers, regardless of traffic situations as in downtowns.
Technology in which a super capacitor is connected to a battery in a vehicle and voltage of the battery is stabilized using charged voltage of the capacitor has been introduced to solve such problems.
Electric Double Layer Capacitors (EDLC), which are high-capacitance capacitors, are advantageous over general batteries in that they exhibit performance of more than 100 times in supplying instantaneous peak power for a very small time although they can store smaller energy than batteries.
If such advantages are applied to the battery, it is possible to efficiently cope with instantaneous voltage decrease of the battery which occurs within several seconds, thereby supplying high-quality power to a sensitive load. This not only achieves power stability but also assists the battery, extending the lifespan of the battery.
However, since the high-capacitance capacitor has a high capacitance of several to thousands of farads (F), current in a range of tens to thousands of amperes (A) flow when the high-capacitance capacitor is charged, causing instantaneous voltage decrease. In addition, the high-capacitance capacitor also affects charged voltage of the battery due to overload of the generator, failing to improve mileage, although output and noise reduction are improved.
Since a power stabilization apparatus which simply uses the conventional high-capacitance capacitor causes battery or generator overload, exerting a negative influence on mileage, power stabilization apparatuses mostly employ a small-capacitance capacitor rather than a high-capacitance capacitor. However, it was found that the small-capacitance capacitor provides almost no improvement in mileage or performance when battery voltage instantaneously drops since fuel rate is determined after the ECU of the vehicle performs learning.